This invention relates to novel polymers and more particularly to high performance polymers provided by cross-reaction of an inorganic with an organic oligomer.
Oxirane oligomers are known to be very useful for meeting high performance needs in fabricating structural composites, protective coatings, adhesives, castings, laminating, electrical potting compounds and the like. The performance and utility of oxirane polymers are also known to be dependent upon their chemical structure, the curing agent used and conditions of cure. One important factor is achieving a high performance polymer is often the chemical structure of the polymer.
With proper formulation, polymer systems can be produced having enhanced properties in areas such as chemical and corrosion resistance, high adhesive strength, high heat deflection temperatures and toughness. These properties are often based on the crosslink density capabilities of the particular oligomer or prepolymer used. Usually, the higher the crosslink density, the higher the chemical and corrosion resistance, the higher the adhesive strength, the higher the mechanical strength, the higher the heat deflection temperature and the better the toughness.
One oxirane oligomer having a very low molecular weight and compact structure is diglycidyl ether of resorcinol (DGER), i.e.,; 1,3-BIS-(2-3 epoxy propoxy) benzene, which has the following structure: ##STR1##
Diglycidyl ether of resorcinol has an epoxide equivalent of between 120 and 135 and a viscosity at 25.degree. C. of between 300 and 500 CPS. The small molecular size leads to the low expoxide equivalent and indicates that the molecule can achieve a high final crosslink density.
Another oxirane oligomer is a low molecular weight diglycidyl ether of bisphenol A, having an epoxide equivalent between 172 and 176 and a viscosity at 25.degree. C. between 4000 and 6000 CPS. This compound has the following structure: ##STR2##
As already noted, both of these oxirane oligomers are known to be useful in preparing higher molecular weight crosslinked polymers. For example, U.S. Pat. No. 4,383,060 to Dearlove teaches an epoxy adhesive comprising an epoxy novolac resin, an epoxy flexibilizer, natural and colloidal silica and an imidazole curing agent. U.S. Pat. No. 4,499,217 to Yoshimura et al. is directed to a thermosetting resinous liquid compositions comprising a composite formed from a dispersion of silica colloid in alcohol and a thermosetting resin such as an epoxy-phenol. U.S. Pat. No. 4,486,558 to Guilbert discloses an electrically insulating powder comprising a blend of (1) a derivative of a polyglycidyl ether of bisphenol A and (2) finely divided silica, while U.S. Pat. No. 4,574,132 to Sayles describes an adhesive comprising (1) diglycidyl ether of bisphenol A, (2) diglycidyl ether of 1,4 butanediol, and (3) silica.
U.S. Pat. No. 4,748,300 to Lalancette is directed to a polyhydroxysilicate-polymer reaction product. The product is prepared by reacting a finely divided polyhdroxysilicate and a hydroxy-containing polymer. The Lalancette product, however, is obtained by reacting the polyhydroxysilicate and a hydroxy-containing polymer without the use of a coupling agent and the teaching stresses the elimination of the coupling agent. The resultant material is, in any case, a completely polymerized mass.
A great deal of work has been conducted with respect to the use of oxirane polymers, but little or no work has been done directed to chemically bonding an inorganic oxide to an organic oxirane polymer and, insofar as is known, none on the use of partial polymerization of the hydroxyl group of the inorganic and the oxirane group. This cross-linking of the inorganic oxide, with the organic oligomer, through partial polymerization can eliminate undesirable characteristics which result with mere physical blending and adds the beneficial properties of chemical bonding, while maintaining a prepolymer capable of being fully polymerized at a later date.